The pattern of endoproteolytic activities following Sorghum bicolor (cv. Giza 10) grain germination was studied. The maximum activity of acidic, neutral and basic of sorghum endoproteases was observed on days 6, 4 and 8 of germination, respectively. The effect of class-specific inhibitors on the endoproteolytic activities during grain germination, assyed in solution with azocasein as a substrate, indicated that: a) Metalloendoproteases were detected from day 6 to day 10 of germination, using ethylenediaminetetraacetic acid (EDTA)as an inhibitor, b) Aspartic endoproteases were detected from day 10 to day 14 of germination, using pepstatin A as an inhibitor, c) Serine endoproteases were detected at all stages ofgermination, using phenylmethyl sulphonyl fluoride (PMSF) as an inhibitor, d) Tiol endoproteases were detected from day 2 to day 6 of germination, using iodoacetate (IA) and p-Hydroxymercuribenzoate (p-HMB) as inhibitors. The effect of class-specific protease inhibitors was also tested on endoprotease assays in electrophoretic gel. The endoproteolytic bands of Sorghum bicolor grain germination were arbitrarily clasified into three groups A, B and C contained less or more than 8 bamds. Group B and, to a lesser extent, group C are contained metallo, serine and thiol endoproteases. this work shows that germinating Sorghum bicolor contains a complex set of endoproteases could be potentially a good starting material for preparation of different classes of endoproteases.

Key words: endoproteases, inhibitors, Sorghum bicolor